ABSTRACT Opioid overdose is a major public health crisis, and a clear sign of problem drug use. Many people who experience an overdose receive a naloxone reversal and are treated in a hospital emergency department. However, few overdose survivors enroll in treatment, even if they receive care and referral to treatment while in an emergency department. Medication assisted treatments (MAT), such as methadone or buprenorphine, are among the most effective treatments for opioid use disorder, and effectively prevent overdose. Promoting entry into MAT in people who received a naloxone reversal and overdose-related care in an emergency department could reduce the risk of additional overdose. Contingency management (CM) interventions have successfully improved a broad range of health behaviors including medication adherence and treatment attendance. In CM, incentives are made available contingent upon objective verification that the patient has engaged in a specified target behavior. For example, a participant could receive cash or prizes in exchange for a drug toxicology test that indicated recent drug abstinence. We believe a similar approach could promote entry into MAT. If it does, then we believe the intervention will be of substantial interest to health care payers. Thus, the purpose of this study is to develop a smartphone-based intervention to promote MAT entry and engagement for people with opioid use disorder. We will specifically target people who received naloxone reversal and care in an emergency department. The applicant organization, DynamiCare Inc., is at the leading edge of the development and commercialization of low-cost, highly scalable CM technology and associated implementation for substance use disorders. We have a fully functional, field-tested intervention that facilitates CM adoption by lifting the burden of effort from the provider and placing control in the hands of the patient. To date, our focus has been on developing and evaluating this system to promote longitudinal retention and abstinence. Under this application we intend to address the challenge of acute care motivation for initiation and engagement with MAT. Thus, in addition to our app's current robust array of features, we will need to add several others: a system for prompting users with incentives to input self-generated reasons for seeking treatment and potential benefits of treatment, and a reframing of our existing selfie video system for salivary drug toxicology testing as a system for medication adherence. We will manualize the intervention for deployment in emergency departments. After the intervention has been tailored to the target population and the manual has been developed we will conduct a pilot study (N = 20) in naloxone reversal patients who seek treatment in emergency departments in Kalamazoo, MI. The intervention will be available for up to two months. Incentives will be supplied for key treatment seeking behaviors, engagement behaviors, and MAT adherence. The intervention and technology will be revised as needed to prepare for Phase II and ultimate commercialization.